The present invention relates generally to ultrasonic proximity switches, and more particularly to an ultrasonic proximity switch having a transmitting oscillator, whose transmitting frequency is periodically modulated by a first transmitting clock pulse for a constant transmitting time to a transmitting stage.
DE 27 21 254 discloses such an ultrasonic proximity switch. Usually, ultrasonic proximity switches are connected to evaluation electronics, which evaluate the transmitting and receiving signal of the ultrasonic proximity switch. Up until now, the procedure had been to generate the transmitting clock pulse in the evaluation electronics and to then feed it to the ultrasonic proximity switch. This entailed additional circuitry in order to produce the transmitting clock pulse. In terms of hardware, this additional circuitry was either analog or digital circuits, or software combined with a microprocessor.
The present invention is directed to the problem of developing an ultrasonic proximity switch having a transmitting oscillator, whose transmitting frequency is periodically modulated by a first transmitting clock pulse for a constant transmitting time to a transmitting stage without the need for additional circuitry and thereby reducing the related expenditure.